Ranking of query results is one of the fundamental issues in information retrieval, the scientific/engineering discipline behind search engines. Given a query q and a collection D of documents that match the query, the problem is to rank, (i.e., sort) the documents in D according to some criterion so that the “best” results appear early in the result list displayed to the user. Typically, ranking criteria are phrased in terms of relevance of documents with respect to an information need that is expressed in the query.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.